This invention relates to chucks and similar tool holders for releasably holding tools such as drill bits to manual or powered drivers. More particularly, the invention relates to removable nosepieces for chucks and similar tool holders such as collets.
Many chucks are now being constructed with exposed rubber or plastic parts or surfaces. For example, such chucks may have one or more exposed rubber or plastic parts or surfaces that are gripped by the user to tighten or loosen the chuck. The use of rubber or plastic in this way has several advantages over all-metal construction. One advantage is that the weight of the chuck tends to be reduced. Another advantage is that material cost for the chuck may be lowered. Still another advantage is that the greater coefficient of friction of rubber or plastic as compared to metal makes the chuck easier to operate without the need for a key or other appliance to tighten the chuck on a tool or to subsequently loosen the chuck to release the tool.
A possible disadvantage of exposed rubber or plastic parts or surfaces is that they tend to wear more easily, more rapidly, and more severely than similarly located metal parts or surfaces. An area in which such wear tends to most rapid and severe is adjacent the distal end or "nose" of the chuck. It is here that the chuck is most frequently impacted by flying debris from the work being performed by the tool gripped by the chuck. The rapidly rotating nose of the chuck may also suddenly come into contact with a stationary workpiece when the tool held in the chuck breaks through the workpiece. This may cause considerable wear on or damage to rubber or plastic on the nose of the chuck.
In view of the foregoing, it is an object of this invention to provide improved chucks with plastic or rubber parts or surfaces.
It is another object of this invention to facilitate protection and/or renewal of rubber or plastic parts of a chuck, especially at or near the nose of the chuck.